JP2976264B2 - Injection molding method of three-layer structure molded article and its mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a first layer, a third layer,
The present invention relates to an injection molding method for a three-layer structure molded article, which is formed by injection-molding a three-layer structure molded article including an intermediate layer between these layers, and a mold therefor.

[0002]

2. Description of the Related Art Plastic products are used in a wide variety of applications, and there is also a need for molded articles having a three-layer structure in which physical properties or colors are partially different. A molded product S having such a three-layer structure generally has a first layer A, an intermediate layer B, and a third layer C, as shown in FIGS.
Are injection-molded by different molds, and the contact surfaces of the layers A, B, and C are joined or welded with an adhesive to form a molded product S having a three-layer structure.

[0005] On the other hand, FIG.
As shown in each step (c), a pair of dies 4
There is also known a method of forming the third layer C by secondary injection molding by using 0 and 42. That is, in the first step, the movable mold 4
0, a first layer A and an intermediate layer B, which have been molded in different molds in advance, are sequentially inserted using a guide rod or a positioning rod 41, and are clamped with an intermediate mold 42 in a second step. As shown in (b) in the process, the third layer C is formed by injecting the molten resin from the nozzle 43 into the space above the intermediate layer B inserted through the runner 44 of the mounting plate 46, There is also known a method of taking out a molded product S having a three-layer structure by the ejecting device 45 after cooling and solidification.

Further, as shown in FIG. 6, a method of injection-molding the intermediate layer B using a mold in the same manner is also known. According to this method, the preformed third layer C is inserted into the cavity 51 of the movable mold 50,
The first layer A similarly molded in advance is inserted above it and clamped to the intermediate mold 54 as shown in (b). At this time, the flange A 'of the first layer A is locked to the step 52 of the cavity 51, and the upper surface of the third layer C is
A space for forming the intermediate layer B is secured between the lower surface of the layer A and the lower layer. Therefore, when the molten resin is injected from the injection nozzle 53, the resin is injected into the space between the upper surface of the third layer C and the lower surface of the first layer A through the runner 55 and the gate 56 of the intermediate mold 54, B is molded. After the cooling and solidification, the mold is opened and the ejected device 57 takes out the molded product S having a three-layer structure, as shown in FIG.

[0005]

As described above, a molded article S having a three-layer structure can be formed by the conventional method, but has various drawbacks. For example, the first layer A, the intermediate layer B, and the third layer C are formed by different molds, respectively, and the contact surfaces of these layers A, B, and C are joined or welded with an adhesive to form a three-layer structure. The method of forming the molded product of (1) requires three types of dies to form these layers A, B, and C, and has a disadvantage that the cost of the dies increases. In addition, an adhesive, a welding device, and the like are required, so that the processing steps and the molding cycle become longer. Therefore, there is a disadvantage that labor costs are also increased.

On the other hand, the conventional molding method using a mold has the same disadvantage. That is, according to the method of injection-molding the third layer C described with reference to FIG. 5, two dies for pre-forming the first layer A and the intermediate layer B are required, and the third layer C is further injected. A mold for molding is also required.
Moreover, even if the third layer C is formed, the first layer A and the intermediate layer B are not fused, so that the first layer A and the intermediate layer B are bonded or welded before or after the injection molding of the third layer C. There is a need.
In addition, it takes time and effort to insert the first layer A and the intermediate layer B into the mold 40, and the molding cycle becomes longer. Further, there is a disadvantage that in the step of closing the mold, the position of the insert, that is, the position of the first layer A and the intermediate layer B is shifted or separated from the mold, so that troubles in molding are likely to occur. According to the method of injection molding the intermediate layer B described last, the intermediate layer B
When injection molding is performed, the intermediate layer B, the first layer A and the third layer
Since layer C is welded, the problem of adhesion is eliminated,
In order to form the layer A and the third layer C, respectively, and to form the intermediate layer B, a total of three types of dies are required, which also has the disadvantage of increasing the cost of the dies. When the number of molds is large, the molding cycle is lengthened, and the cost remains high. Furthermore, there is a problem of trouble on the insert.
As described above, the conventional methods have disadvantages in that the molding cycle is lengthened and the productivity is reduced. Therefore,
An object of the present invention is to provide an injection molding method of a three-layer structure molded article which can be molded in a short cycle at a low cost, and a mold therefor.

[0007]

In order to achieve the above object, the invention of an injection molding method comprises a first mold 1 for molding a first layer A and a third mold 5 for molding a third layer C. And a second slide mold 10 that is slidably provided between these molds 1 and 5 and that forms the intermediate layer B. In the primary injection molding, the cavity of the second slide mold 10 is used. With the molten resin 11 closed, the cavities 2 and 3 of the first mold 1
The first layer A and the third layer C are injected into the cavity 6 of the mold 5.
And in the second injection molding, the second slide mold 1
0 is the cavity 11 and the cavity 2 of the first mold 1 is
And the mold is slid to a position matching the cavity 6 of the third mold 5, and the molten resin is injected into the cavity 11 of the second slide mold 10 to form the intermediate layer B. The invention according to claim 2 is characterized in that the first mold 1 and the third mold
The first mold 1 includes a mold 5 and a second slide mold 10 slidably provided between the molds 1 and 5. The first mold 1 is formed with a first layer A. The first cavity 2 has a third mold 5 for forming a third layer C.
A cavity 6 and an intermediate cavity 11 for forming an intermediate layer B and a through hole 12 are formed on the second slide mold 10.
The second slide mold 10 is provided with a cavity 11 having a cavity 11 aligned with the cavity 2 of the first mold 1 and the cavity 6 of the third mold 5, and a through hole. 12 is configured to be slidable to a matching position.

[0008]

The second slide mold 10 is slid to align the through holes 12 of the second slide mold 10 with the cavities 2 of the first mold 1 and the cavities 6 of the third mold 5. Then clamp the mold. When the molds are clamped, the cavities 2 of the first mold 1 and the cavities 6 of the third mold 5 are cut off by the second slide mold 10. The molten resin is injected into the cavity 2 of the first mold 1 and the cavity 6 of the third mold 5 by inserting, for example, a runner. Then, the first layer A is formed by the cavity 2 of the first mold 1 and the third layer C is formed by the cavity 6 of the third mold 5. After cooling and solidification, the mold is loosened, the runner is taken out if necessary, and the second slide mold 10 is moved to the cavity 11 of the first mold 1 and the cavity 6 of the third mold 5. Slide to the alignment position. Similarly, the mold is clamped and the molten resin is injected through the runner. Since the first layer A and the third layer C are already injection-molded in the cavity 2 of the first mold 1 and the cavity 6 of the third mold 5, the molten resin is supplied to the second slide mold 10. The intermediate layer B is formed by being injected only into the cavity 11. After being cooled and solidified, the mold is opened, and the three-layer structure molded product S is taken out. Hereinafter, the same operation is repeated to mold.

[0009]

Embodiments of the present invention will be described below. As shown in FIG. 3, the three-layer structure molded product S formed according to the present embodiment includes a first layer A having a relatively large diameter and a third layer A having the smallest diameter.
It is formed from a layer C and an intermediate layer B between these layers A and C. A through-hole is formed at the center of the three-layer structure molded product S. Examples of molds for injection molding are:
This is shown in FIG.

The mold according to this embodiment includes a first mold 1 for molding the first layer A, a third mold 5 for molding the third layer C, and a first mold 1. It is provided slidably between the third mold 5 and includes a second slide mold 10 for forming the intermediate layer B, an intermediate mold 20, an attachment plate 30, a locate ring 31, and the like. These dies 1, 5, 10, and 20 are not shown in the figure, but are appropriately driven in a mold opening direction or a mold clamping direction by a conventionally known means. The first mold 1 has a first layer A
And has a cavity 2 for molding. The cavity 2 has a through-hole shape, and a stepped portion 3 having an enlarged diameter for forming a flange portion A ′ of the first layer A is formed above the cavity 2. The third mold 5 is provided with a concave cavity 6 for molding the third layer B, and an upwardly extending bar-shaped projection 3 is formed at a substantially central portion of the cavity 6. The rod-shaped projection 3 forms a center hole of the third layer C and also positions a runner of the intermediate mold 20 described later. The cavities 2 and 6 are tapered as a whole.

The second slide mold 10 has the same thickness as the intermediate layer B and is located between the first mold 1 and the third mold 5. Then, although not shown in the drawing, for example, a die slide hydraulic mechanism is slidably driven in the horizontal direction and left and right. The second slide mold 10 has a through-hole cavity 11 for forming the intermediate layer B.
Are formed, and a through hole 12 is provided at a position where the hole does not interfere with the cavity 11. A runner to be described later is inserted into the through hole 12 at the time of primary injection molding. The intermediate mold 20 has a cavity 2 of the first mold 1 when the mold is clamped,
Cavity 6 of third mold 5 and second slide mold 1
A runner 21 is provided to be inserted into the cavity 11 or the through hole 12 of the zero. When the molds are similarly clamped, the cavities 2 and 3 of the first mold 1
Gates 22 and 23 that open in the cavity 6 of the mold 5 and the cavity 11 of the second slide mold 10, respectively;
24 are formed. A sprue 32 communicating with the runner 21 is formed on the mounting plate 30, and a locate ring 31 is mounted on the outside.

Next, an injection molding method of the three-layer structure molded product S using the above-mentioned mold will be described. As shown in FIGS. 1A and 1B, the through hole 1 of the second slide mold 10 is provided.
2 slides to a position matching the cavity 2 of the first mold 1 and the cavity 6 of the third mold 5 by, for example, a die slide hydraulic mechanism. Then, the mold is clamped by a mold clamping device not shown. When the mold is clamped, the tip of the runner 21 is positioned by engaging with the bar-shaped protrusion 3 provided upward at substantially the center of the cavity 6 of the third mold 5.
Since the positioning is performed in this manner, it is possible to obtain an injection-molded product with less post-processing such as deburring. The molten resin J is injected from the injection nozzle 33 by a conventionally known method (primary injection molding). Then, the resin flows from the sprue 32 of the mounting plate 30 through the runner 21 of the intermediate mold 20 to the gate 2.
2 is injected into the cavity 2 of the first mold 1. At the same time, it is injected into the cavity 6 of the third mold 5 from the gate 24. Since the gate 23 is closed by the peripheral wall of the through hole 12 of the second slide mold 10, it is not injected from the gate 23. The first layer A and the third layer C are formed by this primary injection molding.

After cooling and solidifying, as shown in FIG. 2A, the first mold 1, the third mold 5, and the mounting plate 3
0 is appropriately separated, and the runner resin R is taken out. Also the second
The cavity 11 of the slide mold 10 is slid to a position matching the cavity 2 of the first mold 1 and the cavity 6 of the third mold 5. Then, the mold is similarly clamped by the mold clamping device. Also at this time, the tip of the runner 21 is positioned by engaging with the bar-shaped protrusion 3 provided upward at the substantially central portion of the cavity 6 of the third mold 5. (B) of FIG.
As shown in (2), the molten resin J is injected from the injection nozzle 33 '(secondary injection molding). Then, the resin flows from the sprue 32 of the mounting plate 30 to the runner 2 of the intermediate mold 20.
1 and is injected from the gate 23 to the cavity 11 of the second slide mold 10. Since the gates 22 and 24 are respectively closed by the first layer A and the third layer C which have already been molded, no molten resin is injected from these gates 22 and 24. The intermediate layer B is formed by this secondary injection molding.

After cooling and solidification, as shown in FIG. 3, the first mold 1, the third mold 5 and the intermediate mold 20 are opened, and the three-layered molded product S is taken out by the ejector device 35. . Hereinafter, the same operation is repeated to perform injection molding.

[0015]

As described above, according to the present invention, the first mold for forming the first layer, the third mold for forming the third layer,
In the primary injection molding using a second slide mold that is slidably provided between these molds and molds an intermediate layer, the molten resin is sealed in a state in which the cavity of the second slide mold is closed. Is injected into the cavities of the first mold and the cavities of the third mold to form the first and third layers. In the second injection molding, the cavities of the second slide mold are moved to the first and third cavities. Since the molten resin is slid to a position matching the cavities of the mold and the cavities of the third mold, and the molten resin is injected into the cavities of the second slide mold to form the intermediate layer.
A set of a mold, a third mold, and a second slide mold,
A three-layer structure molded article can be formed. Since the number of the dies is small, the cost of the dies is low, and the injection cycle is short and the productivity is improved. Furthermore, according to the present invention, since the intermediate layer is injection-molded in the secondary injection molding, the first layer and the third layer are fused to the intermediate layer, eliminating the need for a bonding step which increases the cost as in the conventional case. Become. The invention of claim 2 comprises a first mold, a third mold, and a second slide mold slidably provided between these molds. A first cavity for molding the first layer, a third cavity for molding the third layer in the third mold, and an intermediate cavity for molding the intermediate layer in the second slide mold. And a through hole, respectively, and the second slide mold has a cavity
Since it is slidable between a position where the cavities of the first and third molds are aligned with each other and a position where the through holes are aligned, the primary injection molding is slid to the position where the through holes are aligned and the secondary injection molding is performed. In injection molding, a three-layer molded article by primary or secondary injection molding can be molded in a short cycle at low cost simply by sliding to the position where the cavities match.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing an embodiment of the present invention. FIG. 1 (a) is a schematic sectional view showing a state in which a mold is clamped for primary injection molding. FIG. 2 is a schematic cross-sectional view showing a primary injection molding state.

It was Tsu Owa primary injection molding by Figure 2 the mold of this embodiment
It is a figure which shows a state, (a) is sectional drawing which shows typically the state which opened the metal mold | die and slided the 2nd slide metal mold | die, and (b) is the schematic which shows a secondary injection molding state. FIG.

FIG. 3 is a schematic cross-sectional view showing a state in which the mold of the present embodiment is opened and a three-layer structure molded product is taken out.

FIG. 4 is a view showing a molding method of a three-layered molded product by conventional bonding, in which (a) decomposes each layer and (b)
FIG. 4 is a perspective view showing a state in which it is joined.

FIG. 5 is a view showing a molding method of a three-layer structure molded product using a conventional mold, in which (a) shows a state in which a primary injection molded product is inserted into a mold, and (b) shows a secondary injection molded state. And (c) is a schematic cross-sectional view showing a state in which the mold is opened to take out a three-layer structure molded product.

6A and 6B are diagrams showing another molding method of a three-layer structure molded product using a conventional mold, wherein FIG. 6A shows a state in which a primary injection molded product is inserted into the mold, and FIG. It is a typical sectional view showing the next injection molding state, and (c) shows the state where the mold is opened to take out the three-layer structure molded product.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 first mold 2 cavity for forming first layer 5 second mold 6 cavity for forming third layer 10 second slide mold 11 cavity for forming intermediate layer 12 through hole A first layer B intermediate layer C 3rd layer S 3 layer structure molded product

Claims (2)

(57) [Claims] 1. A first mold 1 for molding a first layer A;
Primary injection molding using a third mold 5 for molding the layer C and a second slide mold 10 slidably provided between the molds 1 and 5 for molding the intermediate layer B Then, the molten resin is injected into the cavity 2 of the first mold 1 and the cavity 6 of the third mold 5 in a state where the cavity 11 of the second slide mold 10 is closed, and the first layer A is formed.
And the third layer C. In the second injection molding, the second slide die 10 is replaced with the cavity 11 by the cavity 2 of the first die 1 and the third die 5.
Injection molding of the three-layer structure molded product S by sliding the molten resin into the cavity 11 of the second slide mold 10 to form the intermediate layer B by sliding the molten resin into a position matching the cavity 6 Method. 2. A first mold 1, a third mold 5, and a second slide mold 10 slidably provided between these molds 1, 5, and said first mold 1 and said third mold 5 are provided. The mold 1 has a first cavity 2 for molding the first layer A, the third mold 5 has a third cavity 6 for molding the third layer C, and a second slide mold 10. Are provided with an intermediate cavity 11 and a through hole 12 for molding the intermediate layer B, respectively.
Can be slid to a position where the cavity 2 of the first mold 1 and the cavity 6 of the third mold 5 are aligned, and to a position where the through hole 12 is aligned. S mold for injection molding.